Ultra high frequency translator



mwm m efiwum RM ivylyii 'ay 3, 1955 G. D. O'NEILL 2,707,750

ULTRA HIGH FREQUENCY TRANSLATOR Filed June 8, 948 I 2 Sheets-Sheet l I ljl l l Q 1 R 0 WJMZM Aflorney y 3, 1955 G. D. O'NEILL 2,707,750

ULTRA HIGH FREQUENCY TRANSLATOR Filed June a. 1948 2 Sheets-Sheet 2 INV,ENTOR. fieol' efl. aA/eill Bylaw a'j- Attorney ULTRA HIGH FREQUENCY TRANSLATOR George D. ONeill, Manhasset, N. Y., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application June 8, 1948, Serial No. 31,614

10 Claims. (Cl. 250-13) This invention relates to high-frequency apparatus, including signal generators, signal receivers, and devices such as transceivers for concurrently or successively generating and receiving signals. These signalling devices may be collectively regarded as high-frequency translators. An object of this invention is to devise a novel, simplified, compact and rugged high-frequency translator.

Apparatus of this kind commonly includes a resonator coupled to an energy receiving element such as an antenna or a coaxial transmission line. In the case of an antenna as the energy receiving element, the resonator will supply energy for propagation into free space, or the energy received from free space will be injected into the resonator; or the antenna may concurrently receive energy both from the resonator and from space. The energy receiving element may communicate between the resonator and a load or alternatively a source of generated or reflected energy.

The resonator and the energy receiving element ordinarily are of diiferent characteristic impedances. A further aim of the present invention is to provide a novel and etfective impedance transformer, which in a more specific aspect is especially suited to coupling the resonator to the antenna of the translator in the first mentioned aspect of this invention. It is a broader object of this invention to devise a novel impedance transformer for coupling two high-frequency systems having diiferent characteristic impedances where both systems utilize endwise abutting central conductors. In accordance with this phase of the invention, the systems to be coupled are divided by a common conductive wall and utilize a conductor penetrating that wall centrally of an aperture therein, with one or more metal spokes or arms joining the central conductor to the edge of the aperture. This construction is believed to operate as an inductive coupler comparable to the auto-transformer familiar in lumpedconstant circuits.

nited States Patent A further phase of the present invention is addressed to features in my application Serial No. 681,454, filed July 5, 1946, of which this application is a continuationin-part. That application discloses several forms of resonator-and-dynatron combinations. The dynatron is an electron-discharge device having plural electrodes including a cathode, a grid, and a dynode or secondary emitting electrode. The general principle of the dynatron circuit is described in the Proceedings of the Institute of Radio Engineers for February, 1918, volume 6, page 5. Several arrangements by means of which the dynatron can be used at high frequencies are disclosed in my copending application identified above. The present application contains subject matter in common with that application and includes extensions of certain of the common features. As will be understood, various features of construction here disclosed have broader application than to the dynatron circuit described and illustrated in the following part of this specification, although they contribute notably to the proficiency and structural excellence of the apparatus to be described.

2,707,750 Patented May 3, 1955 Fig. l is an elevation, half in section, of a novel dynatron translator, including a novel impedance transformer, and represents a preferred but illustrative form of the invention in its several aspects;

Fig. 2 is a plan view of a component in Fig. 1;

Fig. 3 is a longitudinal section of a modified or generalized form of the impedance transforming coupler; and

Fig. 4 is a vertical central section of a dynatron combined with a cavity resonator as shown in my aforesaid copending application.

Referring now to Figs. 1 and 2 a novel form of dynatron is shown in combination with a resonator, an antenna and an impedance transformer between the resonator and the antenna. In Fig. l, the dynatron consists of a filamentary cathode 10, an electrode 12 termed a grid and conveniently formed of wire mesh, and a secondary-emissive electrode 14 herein termed a dynode. The grid accelerates the primary electron stream from the cathode to the dynode and also serves to collect the secondary electrons emitted by the dynode. Cathode 10 is provided with a pair of terminals only one of which 16 is shown, the cathode leads being sealed hermetically in glass wall 18 forming part of the envelope of the dynatron. Grid 12 is carried by a metal annulus 20 which also constitutes an external terminal for that grid. The active part of dynode 14 is carried by rod 22 that also acts as the external terminal for the dynode. A cylindrical will 24 having flange 26 is peripherally united with terminal 20 of grid 12, and the upper portion of the dynode envelope is completed by a non-conducting wall 28 normally of glass hermetically sealed to rod 22 and to metal wall 24. The lower envelope wall is completed by joining flanged metal cylinder 30 to grid terminal 20 and to glass wall 18.

If a fixed potential diflerence is established between cathode 10 and grid 12 to make the latter positive, and various static voltages are applied to dynode 14, the dynode current will be observed to increase gradually. After a certain point the dynode current will decrease almost linearly to a minimum, even reversing direction, and thereafter it will increase again. This may be understood by recognizing the composite character of the dynode current, including a part of the primary electron emission leaving cathode 10 which penetrates the interstices of grid 12 to impinge upon the dynode; and, subtracted from this, is the secondary electron emission resulting from this primary electron bombardment. Characteristic curves are shown in my copending application mentioned above. Between certain limits, the decrease of current drawn by the dynode and finally the true reversal of current in the dynode as the dynode potential is increased shows the dynatron to be a negative resistance device. This negative resistance characteristic can be variously used, as for amplifying, for detecting, and for modulating. In Fig. 1, certain portionsi of the dynatron are utilized in a resonator joined to gridt 12 and dynode 14. By adjusting the dynode directcurrent potential to a proper value, this single resonator can be made effective to apply a high-frequency voltage to the dynode in addition to its direct-current potential, and by virtue of the negative resistance characteristic the resonator and dynode in combination can be operated as a high-frequency oscillator. By shifting the voltage on the grid or the dynode to an asymmetrical part of the characteristic, the dynatron will both generate oscillations and detect modulation of received signals; or it will cross-modulate two applied signals.

Surrounding metal wall 24 is a bypass structure generally designated 32. Metal end wall 34 opposite terminal 22 and spider 36, also of metal, complete the resonator enclosing the dynode-grid part of the dynatron. Bypass 32 comprises an inner metal wall 38 and an outer metal wall 40 radially separated by dielectric layer 42 and joined to end wall 34 of the enclosure. Walls 38 and 40 may be regarded as a grooved cylinder spaced by dielectric layer 44 from dynatron wall 24 and this dielectric-filled groove is designed to be electrically a shorted quarter-wave line at the mean operating frequency of the resonator. Similarly walls 24 and 38 with their separating dielectric layer, and with the radial flange 26 are designed as an open-ended quarter-wave line at the mean operating frequency. The open quarter-wave line furnishes insulation against direct-current and a high impedance at low frequencies between wall 24 and wall 38, and its open termination 46 is transformed at its input 48 as a very low impedance at the operating frequency. This low impedance at input 48 is further reduced by the transformed effect of the short-circuited quarter-wave line connected in series with open termination 46. Somewhat similar arrangements are shown in United States Patents No. 2,679,591 and No. 2,677,057. This bypass construction offers a very low impedance to high-frequency currents at its input 48, but acts as a blocking capacitor at low frequencies and as a directcurrent insulator.

End wall 34 is radially grooved and filled with a dielectric layer 50 to constitute a shorted quarter-wave line 51 at the operating frequency. Wall 34 has a circular aperture 52 centered about rod 22, and is directly connected to that rod by the spokes or arms of metal spider 36.

The resonator that largely determines the operating frequency of the dynode circuit and which applies a signal voltage to the dynode includes the inner surface of ring 20 and of Wall 24, a part of wall 38 where it joins end wall 34, a portion of that end wall 34, spider 36 and rod 22. At the upper end of rod 22 and the shaft 54 of a rod-like antenna is secured which, with wall 34 as a ground plane, is effective to radiate the power generated in the dynatron as an oscillator. The antenna is also effective to receive radiant energy and inject it into the resonator. The shorted quarter-wave line forming part of bypass 32, which is spaced from the open end of line 51, serves to broad-band the effectiveness of each shorted line alone, and confines the coupling between the antenna and the resonator to that provided at spider 36.

The dynatron circuit described is energized by a tapped direct current supply 53, 55 so that cathode 10 is appropriately negative with respect to grid 12, and so that dynode 14 is at the desired part of its characteristic for the service intended. Between supply 53, 55 and dynode 14 a device 57 is shown which is a modulator where generated modulated oscillations are to be transmitted; or device 57 is a utilization device of non-linear impedance where the dynatron circuit is to serve as a receiver of modulated signals or as a detector of changing re flections of radiated oscillations. Utilization device 57 is a feature of the novel dynatron circuit as disclosed in my application Serial No. 681,454.

The signal voltage appearing between electrodes 12 and 14 works into the resonator which, with the coupled load, is designed to present a matching impedance to those electrodes. The characteristic impedance of inner and outer conductors 22, 24 as a coaxial line which is coupled to the antenna is higher than the impedance of the antenna shown. I believe that conductive end wall 34 and spider 36 operate as an inductive coupling somewhat like the familiar auto-transformer known in the commercial power field and in high-frequency lumpedconstant circuits. The end termination of line 22, 24 includes each spoke of spider 36 as a common inductance to the antenna load comprising the outer face of end wall 34, antenna 54, and of course spider 36. The openings between the spokes of spider 36 provide for direct intercommunication of the electro-magnetic fields on both sides of wall 34. The metallic connection between wall 40 and rod 22 afforded by spider 36 provides a direct-current circuit for dynode 14. The entire circuit is such as, structurally, to form a unit free from mechanically unbalanced masses that would inhibit rapid rotation about the axis of rod 22 and antenna 54. (Compare, for example, the unbalanced mass of the output coupling in Fig. 4.)

Fig. 3 illustrates a further application of the inductive coupling afforded by spider 36. In Fig. 3 spider 36 is shown as the common impedance for coupling one coaxial line 22, 24 into a second coaxial line 54, 56 of different characteristic impedance. The two coaxial lines thus coupled utilize a common central conductor (although the portions extending into the two lines need not be of the same diameter). The metallic spider serves as a common impedance for both lines, in a manner which I conceive to be analagous to the common winding of an auto-transformer.

The number of arms in the spider, and their distribution, dimensions and shape, are matters for empirical design. Since the end result is not readily susceptible to computation, the parameters may be experimentally adjusted to balance out reflections; or matching stubs and other comparable expedients may similarly be utilized to perfect the matching of impedances.

Fig. 4 illustrates a dynatron oscillator as disclosed in my application Serial No. 681,454. That oscillator includes a dynatron generally indicated by numeral 60 comprising a glass envelope having an upper portion 62, a lower portion 64, a ring terminal 66 between those envelope portions, a rod terminal 68 through envelope portion 62, and multiple terminals 67 sealed through envelope portions 64. Terminals 67 are connected internally to a filamentary heater 69, and one terminal 67 is also connected to cathode 70. Grid 72 is secured centrally of terminal 66. Dynode 74 is carried internally by rod 68. Dynode 74 is convex, and grid 72 is curved so as to be concave about the dynode but convex on the side facing the cathode. The effect of this construction is in part to divert and remove reflected electrons and primary electrons that would build up space-charge by oscillating back and forth through grid 72, and in part to cause a focusing action on the shape of the electron stream from cathode 70.

The dynatron in Fig. 4 is energized by a direct-current power supply including a first section 76 which energizes the filament 69, a second section 78 which together with section 76 maintains dynode 74 at a potential positive with respect to cathode 70, and a third section 80 which maintains grid 72 positive relative to dynode 74 and much more positive relative to cathode 70. The potentials applied are such that as to utilize the negative resistance characteristic of the dynatron in an oscillator where no utilization device is included.

In order to utilize the dynatron for ultra high frequency signal generation, a resonator is connected between the terminals 66 and 68 of the grid and the dynode respectively, so as to contain those two electrodes in an oscillatory system. The resonator comprises a cylindrical wall 82, an end wall 84 joined to rod 68 and a second end wall 86 coupled by a dielectric layer 88 and annulus 90 which serve as a high frequency bypass. The signal generated is coupled by loop 92 and coaxial line 94 to the load (not shown). The oscillator thus described is highly stable. for all of its components are susceptible to accurate construction and fixed proportions and configuration.

A comparison of Fig. 4 with Fig. 1 will reveal certain significant common characteristics, especially in relation to the association of the dynatron with the resonant circuit. In both cases that circuit is connected between the grid and the dynode, and in both instances a bypass construction is provided for separating the dynode and grid in respect to direct-current energization.

The foregoing detailed discussion is concerned with various specific constructions and modifications embodying certain features of the invention. The several features will be found to be widely useful and detailed modifications and substitutions will occur to those skilled in the art; therefore I desire the appended claims to be given broad interpretation consistent with the spirit of the invention.

What is claimed is:

1. A dynatron translator comprising a cathode, a grid provided with a ring terminal, and a dynode arranged in the order named in a dynatron, a rod supporting said dynode and affording an external terminal, a cylindrical metal wall extending from said ring terminal and about said rod, a non-conducting ring forming a hermetic seal between said rod and the edge of said wall remote from said grid, a metal cylinder encircling said wall but spaced therefrom by a sleeve of dielectrical material, said cylinder being formed with a groove having its opening adjacent said ring terminal, said groove terminating adjacent said edge of said cylindrical wall, said groove being filled with dielectric material, a metal annulus joined to said grooved cylinder remote from said grid, having a radial groove of substantially the same electrical length as said groove in said cylinder, a rod-like antenna extending centrally through said annulus, and a plurality of rotationally balanced metal spokes joining said dynode rod and said antenna to the inner edge of said metal annulus.

2. A dynatron translator comprising a dynatron including a cathode, a grid, and a dynode arranged in the order named along an axis, a rod along that axis supporting said dynode and affording an external terminal, a cylindrical metal wall extending from said grid about said rod to a remote edge, a metal cylinder encircling said wall but spaced therefrom by a sleeve of dielectric material, a groove in said cylinder opening adjacent said grid and terminating adjacent said edge of said cylinder, said groove being filled with dielectric material, a metal annulus joined to said grooved cylinder remote from said grid, said annulus forming part of a resonator that additionally includessaid cylinder, said grid and said dynode rod, an energy-receiving element having a central conductor connected to said rod, and a plurality of metal spokes forming an impedance common to said central conductor and said resonator, and furnishing a directcurrent connection to said dynode rod.

3. A high-frequency translator comprising a dynatron having a cathode, a grid, and a secondary-emitting dynode arranged along an axis in the order named, said grid having an annular terminal and said dynode having a supporting rod extending along said axis, a metal cylindrical wall joined to said annular terminal and extending abount said rod, a non-conducting ring hermetically sealed between said wall and said rod, a centrally apertured conducting wall transverse to said cylindrical wall opposite said annular terminal and forming part of a resonant circuit that additionally includes said rod, said dynode, said grid, said annular terminal, and said cylindrical wall, said end wall and said cylindrical wall being separated by a direct-current blocking bypass construction, an energyreceiving element having a central conductor connected to said dynode rod, and a spoked metal spider joining said apertured end wall to said rod and said central conductor.

4. A translator comprising a cathode, a grid, and a secondary-emissive dynode arranged along an axis in the order named, an annular terminal for said grid, a supporting rod for said dynode, and metallic surfaces connected to said terminal and said rod to constitute therewith a hollow resonator, a direct-current-blocking high-frequency bypassing structure breaching said resonator between said rod and said terminal, an energy receiving element having a conductor extending from said rod centrally through an aperture in said resonator, and a spoked connector between said resonator and said conductor.

5. The combination of a device including a pair of electrodes, a coaxial resonator connected to said electrodes, and an energy receiving element coupled to said resonator, said resonator being breached by a bypass having low input impedance only at high frequencies, and a metal spider coupling said energy receiving element and said resonator together.

6. A high-frequency circuit comprising two portions of different characteristic impedance in endwise abutment each having a central conductor, a centrally apertured wall dividing said portions, the aperture of said wall being centered about said central conductors, and multiple spaced spokes joining said central conductors to the edge of the aperture in said wall.

7. High-frequency apparatus comprising a rod-like antenna, an apertured ground plane, and a coaxial resonator, said antenna and the center conductor of said resonator being joined in endwise abutment and passing centrally through the aperture of said ground plane, and at least one radial conductor joining said antenna and central conductor to the edge of the aperture in said ground plane.

8. In combination an apertured ground plane having a circular aperture, a rod-like antenna extending perpendicularly from said ground plane and passing centrally through the aperture, a metal cylinder extending from said ground plane on the side opposite said antenna, a central conductor within said cylinder in endwise abutment with said antenna, and radial conductors joining said antenna and central conductor to said ground plane at the edges of its aperture.

9. In combination a rod-like antenna, a coaxial resonator having a central conductor in endwise abutment to said resonator, a plurality of radial conductors joining said antenna and central conductor to the outer wall of said coaxial resonator, and a non-linear impedance joining said central conductor and said outer wall at a point displaced from said radial conductors.

10. In combination an electron discharge device, a coaxial resonator having high frequency connection to a pair of electrodes of said device, a rod-like antenna joined to the central conductor of said resonator, an apertured wall joined to the outer conductor of said resonator centrally apertured about said central conductor and said antenna, the aperture in said wall being smaller than the outer conductor of said coaxial resonator thereby to form an end Wall of said resonator said wall being radially extended about said antenna to serve as a ground plane therefor, and a plurality of radial conductors joining said antenna and said central conductor to said ground plane at the edges of its aperture.

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